Keeping it on Newt

12/29/11 9:22 AM EST

The newest salvo from Romney's super PAC auxiliary is aimed at the usual target, Newt Gingrich.

Something to watch for in the closing days: Will the group turn its fire on Rick Santorum? If it does, it would be the clearest sign yet that Romney is playing to win Iowa; Gingrich, however, seems to represent more of a threat in the states to come.